Did my son suffer from stroke due to a fall?

Q:My son is 2 years old & is perfectly normal. A month back, he fell down on the wet floor & injured his head. He cried for sometime & slept. When he woke up we saw his lips going on one side & he couldn't walk properly. His right hand was very weak that he couldn't even switch on the light. We immediately rushed him to the hospital, where the doctors did a CT scan, which was normal. But they asked us to consult a neurologist. Next day a MRI scan showed the following - lesion suggestive of ischaemia. Due to age and absence of record, the possibility of vasculitis should be considered. The doctor said that he had a stroke (hemiparesis), which is not due to the fall, it was present earlier & the fall was just a coincidence. They have taken all the tests including angiogram of brain, echocardiograph and blood & urine tests. But everything was normal. The haematologist said it could be because of the fall. We are confused as none of the doctors here (in Brazil) speak English. He was given physiotherapy for couple of days & became normal within a week. He is perfectly normal now, but I have lots of doubts, which I was not able to ask because of the language problem. What could be the cause of the stroke? Is there any chance of it coming back in the future? Will it come again if he falls? Are there any tests to be done? Do we need to take any precautions to avoid it in future? No one in our family has stroke.

A:What your child suffered was a stroke due to blockage of the deeper arteries of the brain that supply a collection of cells called the basal ganglia. I am confident that the fall was a coincidence. This is not an uncommon problem in infants and toddlers. The good recovery supports my feeling that the basal ganglia were affected. There is excellent chance that this will not recur. You should encourage physiotherapy and avoid massage.
We have not consistently found causes in our patients with similar events. But I would recommend the following tests: